Simple Photocell Power Supply using MAX630

This is a simple and easy build photocell power supply. It uses 8 pieces of photocell and single regulator IC of MAX630. This circuit capable to deliver either 4.8 or 7.2 V regulated at 15 mA with a 3-V input from a bank of photocells. R1 should be 453K Ohm for a 7.2-V output and 274K Ohm for a 4.8-Vdc output. Regulator efficiency of this circuit is about 70%.
The Maxim’s MAX630 CMOS DC-DC regulators is designed for simple, efficient, minimum-size DC-DC converter circuits in the 5mW to 5W range. The MAX630 provide all control and power handling functions in a compact 8-pin package: a 1.31V bandgap reference, an oscillator, a voltage comparator, and a 375mA N-channel output MOSFET. A comparator is also provided for low-battery detection.

Operating current is only 70μA and is nearly independent of output switch current or duty cycle. A logic-level input shuts down the regulator to less than 1μA quiescent current. Low-current operation ensures high efficiency even in low-power battery-operated systems. The MAX630 are compatible with most battery voltages, operating from 2.0V to 16.5V.

Power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Examples of the latter include power supplies found in desktop computers and consumer electronics devices.